First patients treated with a 1.5 T MRI-Linac: clinical proof of concept of a high-precision, high-field MRI guided radiotherapy treatment.

The integration of 1.5 T MRI functionality with a radiotherapy linear accelerator (linac) has been pursued since 1999 by the UMC Utrecht in close collaboration with Elekta and Philips. The idea behind this integrated device is to offer unrivalled, online and real-time, soft-tissue visualization of the tumour and the surroundings for more precise radiation delivery. The proof of concept of this device was given in 2009 by demonstrating simultaneous irradiation and MR imaging on phantoms, since then the device has been further developed and commercialized by Elekta. The aim of this work is to demonstrate the clinical feasibility of online, high-precision, high-field MRI guidance of radiotherapy using the first clinical prototype MRI-Linac. Four patients with lumbar spine bone metastases were treated with a 3 or 5 beam step-and-shoot IMRT plan. The IMRT plan was created while the patient was on the treatment table and based on the online 1.5 T MR images; pre-treatment CT was deformably registered to the online MRI to obtain Hounsfield values. Bone metastases were chosen as the first site as these tumors can be clearly visualized on MRI and the surrounding spine bone can be detected on the integrated portal imager. This way the portal images served as an independent verification of the MRI based guidance to quantify the geometric precision of radiation delivery. Dosimetric accuracy was assessed post-treatment from phantom measurements with an ionization chamber and film. Absolute doses were found to be highly accurate, with deviations ranging from 0.0% to 1.7% in the isocenter. The geometrical, MRI based targeting as confirmed using portal images was better than 0.5 mm, ranging from 0.2 mm to 0.4 mm. In conclusion, high precision, high-field, 1.5 T MRI guided radiotherapy is clinically feasible.

White matter lesions suggestive of amyotrophic lateral sclerosis attributed to celiac disease.

CD is an autoimmune-mediated disorder of the gastrointestinal tract. Initial symptom presentation is variable and can include neurologic manifestations that may comprise ataxia, neuropathy, dizziness, epilepsy, and cortical calcifications rather than gastrointestinal-hindering diagnosis and management. We present a case of a young man with progressive neurologic symptoms and brain MR imaging findings worrisome for ALS. During the diagnostic work-up, endomysium antibodies were discovered, and CD was confirmed by upper gastrointestinal endoscopy with duodenal biopsies. MR imaging findings suggestive of ALS improved after gluten-free diet institution.

Installation of the 1.5 T MRI accelerator next to clinical accelerators: impact of the fringe field.

In the UMC Utrecht a prototype MRI accelerator has been installed to investigate the feasibility of real-time, MRI guided radiotherapy. The system consists of a 6 MV Elekta (Crawley, UK) accelerator and a 1.5 T Philips (Best, The Netherlands) MRI system. The system is installed in a standard radiotherapy bunker. The bunker is at the corner of a block of six bunkers, so there are three neighbouring clinical Elekta accelerators. During ramping of the magnet, the magnetic fringe field in the two nearest bunkers was measured as a function of the magnetic field strength of the MRI magnet. At 8 m, a maximum increase of 1.5 G was measured, at 12 m, 0.6 G. This is up to three times the earth's magnetic field. The clinical accelerators are needed to be re-calibrated in order to operate in such an external magnetic field. The resulting radiation field flatness of the clinical accelerators was measured and was similar to the situation before ramping the magnet.

Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept.

At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system. From the initial design onwards, modifications to both systems were aimed to yield simultaneous and unhampered operation of the MRI and the accelerator. Indeed, the simultaneous operation is shown by performing diagnostic quality 1.5 T MRI with the radiation beam on. No degradation of the performance of either system was found. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MR imaging. The full diagnostic imaging capacities of the MRI can be used; dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door towards a clinical prototype to start testing MRI-guided radiation therapy (MRIgRT) in the clinic.

Wildfire responses to abrupt climate change in North America.

It is widely accepted, based on data from the last few decades and on model simulations, that anthropogenic climate change will cause increased fire activity. However, less attention has been paid to the relationship between abrupt climate changes and heightened fire activity in the paleorecord. We use 35 charcoal and pollen records to assess how fire regimes in North America changed during the last glacial-interglacial transition (15 to 10 ka), a time of large and rapid climate changes. We also test the hypothesis that a comet impact initiated continental-scale wildfires at 12.9 ka; the data do not support this idea, nor are continent-wide fires indicated at any time during deglaciation. There are, however, clear links between large climate changes and fire activity. Biomass burning gradually increased from the glacial period to the beginning of the Younger Dryas. Although there are changes in biomass burning during the Younger Dryas, there is no systematic trend. There is a further increase in biomass burning after the Younger Dryas. Intervals of rapid climate change at 13.9, 13.2, and 11.7 ka are marked by large increases in fire activity. The timing of changes in fire is not coincident with changes in human population density or the timing of the extinction of the megafauna. Although these factors could have contributed to fire-regime changes at individual sites or at specific times, the charcoal data indicate an important role for climate, and particularly rapid climate change, in determining broad-scale levels of fire activity.

Natural and anthropogenic geochemical signatures of floodplain and deltaic sedimentary strata, Sacramento-San Joaquin Delta, California, USA.

The geochemical history of an upper deltaic plain pending tidal wetland restoration was reconstructed to assess remobilization of redox-sensitive constituents in sediment, identify depositional processes promoting geochemical retention, and determine the extent of contamination with Hg, As, Pb, Cu, and Zn. Three 12-14-m sediment cores were analyzed for bulk sediment geochemistry using ICP-AES. Rather than showing similar stratigraphic and geochemical down-core trends, cores had a unique record indicative of strong spatial gradients in deposition processes. Each strata type (e.g. basal clay, sand channel, distal floodplain, and agriculturally impacted surficial horizon) had a unique geochemical "fingerprint". The agriculturally impacted surficial layer showed high [Hg], [As], and [Pb]. The significance is that a restored upper delta will have a complex geomorphology defying conventional criteria of "success" in a restoration framework. Also, there is a significant risk of generating toxic, bio-available CH3Hg+ that would be hazardous to fish.

Fire cycles in North American interior grasslands and their relation to prairie drought.

High-resolution analyses of a late Holocene core from Kettle Lake in North Dakota reveal coeval fluctuations in loss-on-ignition carbonate content, percentage of grass pollen, and charcoal flux. These oscillations are indicative of climate-fuel-fire cycles that have prevailed on the Northern Great Plains (NGP) for most of the late Holocene. High charcoal flux occurred during past moist intervals when grass cover was extensive and fuel loads were high, whereas reduced charcoal flux characterized the intervening droughts when grass cover, and hence fuel loads, decreased, illustrating that fire is not a universal feature of the NGP through time but oscillates with climate. Spectral and wavelet analyses reveal that the cycles have a periodicity of approximately = 160 yr, although secular trends in the cycles are difficult to identify for the entire Holocene because the periodicity in the early Holocene ranged between 80 and 160 yr. Although the cycles are evident for most of the last 4,500 yr, their occasional muting adds further to the overall climatic complexity of the plains. These findings clearly show that the continental interior of North America has experienced short-term climatic cycles accompanied by a marked landscape response for several millennia, regularly alternating between dual landscape modes. The documentation of cycles of similar duration at other sites in the NGP, western North America, and Greenland suggests some degree of regional coherence to climatic forcing. Accordingly, the effects of global warming from increasing greenhouse gases will be superimposed on this natural variability of drought.

Target and non-target ERP disturbances in first episode vs. chronic schizophrenia.

OBJECTIVES: Event-related potential (ERP) abnormalities to target stimuli are reliably found in schizophrenia. However, as people with schizophrenia are thought to have difficulty discerning the relevance of incoming sensory stimuli it is also important to examine ERPs to non-targets. To differentiate between potential trait markers of the disease and deficits that might be associated with the consequence of illness chronicity, this study investigated ERPs to both target and non-target stimuli in groups of people with either first episode or chronic schizophrenia (CSz). METHODS: Using an auditory oddball paradigm, ERPs to target, non-target before target (Nt before) and non-target after target (Nt after) stimuli were analysed for 40 patients with CSz, 40 patients with first episode schizophrenia (FESz) and two groups of normal controls matched for age and sex with their patient counterparts. RESULTS: The FESz group showed the same pattern of amplitude disturbance as the CSz group to both targets (reduced N100, N200, P300 and increased P200) and non-targets (reduced N100) compared to controls. Both CSz and FESz groups also failed to show the changes to the P200-N200 component between targets and non-target stimuli that was exhibited by controls (smaller earlier P200 to targets vs. increased delayed P200 to non-targets) or the reduction in N100 amplitude of ERPs to the Nt after stimuli compared with ERPs to the Nt before stimuli. Previous literature has focussed on the sensitivity of P300 deficits in classifying persons into schizophrenia and non-schizophrenia groups. This study demonstrated improved accuracy in the classification of patients with schizophrenia from controls using discriminant analysis of target and non-target N100 and P200 components. CONCLUSIONS: The results suggest that ERP disturbances are evident at the time of first referral to mental health services and may be a potential trait (rather than secondary effect) of the illness. It is important to include both target and non-target stimuli processing, and their interrelationship in future research.

Responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species vary with site water availability.

We measured responses of leaf respiration to temperature and leaf characteristics in three deciduous tree species (Quercus rubra L., Quercus prinus L. and Acer rubrum L.) at two sites differing in water availability within a single catchment in the Black Rock Forest, New York. The response of respiration to temperature differed significantly among the species. Acer rubrum displayed the smallest increase in respiration with increasing temperature. Corresponding Q(10) values ranged from 1.5 in A. rubrum to 2.1 in Q. prinus. Dark respiration at ambient air temperatures, expressed on a leaf area basis (Rarea), did not differ significantly between species, but it was significantly lower (P < 0.01) in trees at the wetter (lower) site than at the drier (upper) site (Q. rubra: 0.8 versus 1.1 micromol m(-2) s(-1); Q. prinus: 0.95 versus 1.2 micromol m(-2) s(-1)). In contrast, when expressed on a leaf mass basis (R(mass)), respiration rates were significantly higher (P < 0.01) in A. rubrum (12.5-14.6 micromol CO(2) kg(-1) s(-1)) than in Q. rubra (8.6-9.9 micromol CO(2) kg(-1) s(-1)) and Q. prinus (9.2-10.6 micromol CO(2) kg(-1) s(-1)) at both the lower and upper sites. Respiration on a nitrogen basis (R(N)) displayed a similar response to R(mass). The consistency in R(mass) and R(N) between sites indicates a strong coupling between factors influencing respiration and those affecting leaf characteristics. Finally, the relationships between dark respiration and A(max) differed between sites. Trees at the upper site had higher rates of leaf respiration and lower A(max) than trees at the lower site. This shift in the balance of carbon gain and loss clearly limits carbon acquisition by trees at sites of low water availability, particularly in the case of A. rubrum.

beta(1)- and beta(3)-adrenoceptor mediated smooth muscle relaxation in hypothyroid rat ileum.

The effect of hypothyroidism on gastrointestinal beta(1)- and beta(3)-adrenoceptor function and expression was examined in rat ileal smooth muscle preparations. (-)-Isoprenaline and the selective beta(3) agonist disodium (R,R)-5-[2-[[2-3-chlorophenyl)-2-hydroxyethyl]-amino]propyl]-1,3-benzodioxole-2,2-dicarboxylate (CL 316234) relaxed both control and hypothyroid tissues in a dose-dependent manner. Responses to isoprenaline were reduced in tissues from hypothyroid rats, as was the shift produced with the beta(3)-adrenoceptor antagonist, 3-(2-ethylphenoxy)-1-[(1S)-1,2,3,4-tetrahydronaphth-1-ylamino]-(2S)-2-propanol oxalate (SR 59230A). No change was seen in responses to CL 316243. Experiments with a selective beta(1)-adrenoceptor antagonist produced results suggesting that isoprenaline did not act at this receptor. Messenger RNA levels for both beta(1)- and beta(2)-adrenoceptors were not affected by hypothyroidism. These results show that, unlike in adipose tissues, ileal beta(1)- and beta(3)-adrenoceptors are not directly regulated by thyroid hormone and that beta(3)-adrenoceptor coupling to the relaxation response is reduced in a rat model of hypothyroidism.

Requirements for leaf position accuracy for dynamic multileaf collimation.

Intensity modulated radiation therapy can be achieved by driving the leaves of a multileaf collimator (MLC) across an x-ray therapy beam. Algorithms to generate the required leaf trajectories assume that the leaf positions are exactly known to the MLC controller. In practice, leaf positions depend upon calibration accuracy and stability and may vary within set tolerances. The purpose of this study was to determine the effects of potential leaf position inaccuracies on intensity modulated beams. Equations are derived which quantify the absolute error in delivered monitor units given a known error in leaf position. The equations have been verified by ionization chamber measurements in dynamically delivered flat fields, comparing deliveries in which known displacements have been applied to the defined leaf positions with deliveries without displacements applied. The equations are then applied to two clinical intensity modulations: an inverse planned prostate field and a breast compensating field. It is shown that leaf position accuracy is more critical for a highly modulated low-dose intensity profile than a moderately modulated high-dose intensity profile. Suggestions are given regarding the implications for quality control of dynamic MLC treatments.

Identification of sulfated oligosaccharide-based inhibitors of tumor growth and metastasis using novel in vitro assays for angiogenesis and heparanase activity.

Inhibitors of tumor angiogenesis and metastasis are rapidly emerging as important new drug candidates for cancer therapy. To facilitate the identification of such drugs, we recently developed novel and rapid in vitro assays for human angiogenesis and for the extracellular matrix-degrading enzyme heparanase, which has been implicated in tumor metastasis. In this study, sulfated oligosaccharides, which are structural mimics of heparan sulfate, were investigated as drug candidates because these compounds may interfere with heparan sulfate recognition by many angiogenic growth factors and may inhibit cleavage of heparan sulfate by heparanase. In the preliminary screening studies, it was found that inhibitory activity in both assay systems was critically dependent on chain length and degree of sulfation, highly sulfated linear oligosaccharides of five or more monosaccharides in length being the most active. However, two sulfated oligosaccharides stood out as potential antitumor drugs, phosphomannopentaose sulfate (PI-88) and maltohexaose sulfate, both of these compounds having the important property of simultaneously being potent inhibitors of in vitro angiogenesis and heparanase activity. Due to the ease of manufacture of the starting material, phosphomannopentaose, PI-88 was studied in more detail. PI-88 was shown to inhibit the primary tumor growth of the highly invasive rat mammary adenocarcinoma 13762 MAT by approximately 50%, inhibit metastasis to the draining popliteal lymph node by approximately 40%, and reduce the vascularity of tumors by approximately 30%, all of these effects being highly significant. Acute hematogenous metastasis assays also demonstrated that PI-88 was a potent (>90%) inhibitor of blood-borne metastasis. Thus, by the use of novel in vitro screening procedures, we have identified a promising antitumor agent.

Correlates of in-hospital cost among patients undergoing abdominal aortic aneurysm repair.

BACKGROUND: Surgical repair of abdominal aortic aneurysms (AAA) is increasingly being performed, but little is known about the correlates of in-hospital cost associated with this procedure. METHODS AND RESULTS: Baseline clinical characteristics, in-hospital outcomes, and total in-hospital costs were examined among a retrospective cohort of 71 patients who underwent AAA repair. Median age was 68 years, and 75% of the patients were men. High-risk characteristics for perioperative complications were common and included hypertension (73%), documented coronary artery disease (66%), smoking (60%), previous myocardial infarction (47%), history of congestive heart failure (12%), urgent or emergent AAA repair (16%), and diabetes mellitus (11%). Perioperative complications included congestive heart failure (13%), myocardial infarction (11 %), and death (1 %). Median length of stay in the surgical intensive care unit (SICU) was 2 days (range 0 to 28), and median in-hospital stay was 9 days (range 5 to 39). In-hospital cost for the 71 patients ranged from $13,766 to $82,435 (mean $25,931, median $21,633). Univariate and multiple linear regression analyses demonstrated that among the potential correlates investigated, number of SICU days (P= .007) and total length of stay (P< .0001) were the most closely associated with in-hospital cost. CONCLUSIONS: Among patients undergoing AAA repair, the major correlates of in-hospital cost are the number of days spent in the SICU and the total number of days spent in the hospital. These results suggest that any intervention that reduces length of stay may significantly reduce the total in-hospital cost associated with AAA repair.

In vitro biological characterization and antiangiogenic effects of PD 166866, a selective inhibitor of the FGF-1 receptor tyrosine kinase.

Through direct synthetic efforts, we discovered a small molecule that is a nanomolar inhibitor of the human fibroblast growth factor-1 receptor (FGFR) tyrosine kinase. PD 166866, a member of a new structural class of tyrosine kinase inhibitors, the 6-aryl-pyrido[2,3-d]pyrimidines, was identified by screening a compound library with assays that measure protein tyrosine kinase activity. PD 166866 inhibited human full-length FGFR-1 tyrosine kinase with an IC50 value of 52.4 +/- 0.1 nM and was further characterized as an ATP competitive inhibitor of the FGFR-1. In contrast, PD 166866 had no effect on c-Src, platelet-derived growth factor receptor-beta, epidermal growth factor receptor or insulin receptor tyrosine kinases or on mitogen-activated protein kinase, protein kinase C and CDK4 at concentrations as high as 50 microM. PD 166866 was a potent inhibitor of basic fibroblast growth factor (bFGF)-mediated receptor autophosphorylation in NIH 3T3 cells expressing endogenous FGFR-1 and in L6 cells overexpressing the human FGFR-1 tyrosine kinase, confirming a tyrosine kinase-mediated mechanism. PD 166866 also inhibited bFGF-induced tyrosine phosphorylation of the 44- and 42-kDa (ERK 1/2) mitogen-activated protein kinase isoforms in L6 cells, presumably via inhibition of bFGF-stimulated FGFR-1 tyrosine kinase activation. PD 166866 did not inhibit platelet-derived growth factor, epidermal growth factor or insulin-stimulated receptor autophosphorylation in vascular smooth muscle, A431 or NIHIR cells, respectively, further supporting its specificity for the FGFR-1. In addition, daily exposure of PD 166866 to L6 cells at concentrations from 1 to 100 nM resulted in a concentration-related inhibition of bFGF-stimulated cell growth for 8 consecutive days with an IC50 value of 24 nM. In contrast, PD 166866 had little effect on platelet-derived growth factor-BB-stimulated growth of L6 cells or serum-stimulated vascular smooth muscle cell proliferation. Finally, PD 166866 was found to be a potent inhibitor of microvessel outgrowth (angiogenesis) from cultured artery fragments of human placenta. These results highlight the discovery of PD 166866, a new nanomolar potent and selective small molecule inhibitor of the FGFR-1 tyrosine kinase with potential use as antiproliferative/antiangiogenic agent for such therapeutic targets as tumor growth and neovascularization of atherosclerotic plaques.

Cost of cardiac care in the three years after coronary catheterization in a contained care system: critical determinants and implications.

OBJECTIVES: We sought to determine the clinical, angiographic, treatment and outcome correlates of the intermediate-term cost of caring for patients with suspected coronary artery disease (CAD). BACKGROUND: To adequately predict medical costs and to compare different treatment and cost reduction strategies, the determinants of cost must be understood. However, little is known about the correlates of costs of treatment of CAD in heterogeneous patient populations that typify clinical practice. METHODS: From a consecutive series of 781 patients undergoing cardiac catheterization in 1992 to 1994, we analyzed 44 variables as potential correlates of total (direct and indirect) in-hospital, 12- and 36-month cardiac costs. RESULTS: Mean (+/-SD) patient age was 65+/-10 years; 71% were men, and 45% had multiple vessel disease. The initial treatment strategy was medical therapy alone in 47% of patients, percutaneous intervention (PI) in 30% and coronary artery bypass graft surgery (CABG) in 24%. The 36-month survival and event-free (death, infarction, CABG, PI) survival rates were 89.6+/-0.2% and 68.4+/-0.4%, respectively. Median hospital and 36-month costs were $8,301 and $28,054, respectively, but the interquartile ranges for both were wide and skewed. Models for log(e) costs were superior to those for actual costs. The variances accounted for by the all-inclusive models of in-hospital, 12- and 36-month costs were 57%, 60% and 71%, respectively. Baseline cardiac variables accounted for 38% of the explained in-hospital costs, whereas in-hospital treatment and complication variables accounted for 53% of the actual costs. Noncardiac variables accounted for only 9% of the explained costs. Over time, complications (e.g., late hospital admission, PI, CABG) and drug use to prevent complications of heart transplantation became more important, but many baseline cardiac variables retained their importance. CONCLUSIONS: 1) Variables readily available from a comprehensive cardiovascular database explained 57% to 71% of cardiac costs from a hospital perspective over 3 years of care; 2) the initial revascularization strategy was a key determinant of in-hospital costs, but over 3 years, the initial treatment become somewhat less important, and late complications became more important determinants of costs.

Alcohol preference and sensitivity are markedly reduced in mice lacking dopamine D2 receptors.

Although dopaminergic transmission has been strongly implicated in alcohol self-administration, the involvement of specific dopamine receptor subtypes has not been well established. We studied the ethanol preference and sensitivity of D2-receptor-deficient mice to directly evaluate whether dopamine D2 receptors contribute to alcohol (ethanol) consumption. We report a marked aversion to ethanol in these mice, relative to the high preference and consumption exhibited by wild-type littermates. Sensitivity to ethanol-induced locomotor impairment was also reduced in these mutant mice, although they showed a normal locomotor depressant response to the dopamine D1 antagonist SCH-23390. These data demonstrate that dopamine signaling via D2 receptors is an essential component of the molecular pathway determining ethanol self-administration and sensitivity.

Effects of ddC and AZT on locomotion and acoustic startle. I: Acute effects in female rats.

Several synthetic nucleoside analogues, including AZT(RETROVIR), ddC (HIVID), ddI (VIDEX), and d4T (ZERIT), are currently being used in the treatment of HIV infection. Unfortunately, in clinical use the appearance of severe and sometimes debilitating peripheral neuropathy and pain has been associated with the long-term use of several of these drugs (i.e., ddC, ddI and d4T), although not with AZT. To date, standard pre-clinical animal toxicity studies have failed to reveal any adverse neurologic effects of these compounds. However, previously reported preliminary findings suggest that ddC may alter several neuro-behavioral parameters (including locomotor activity, acoustic startle responding, and aggression) in rats and mice following presentation in the animals' drinking water for 7 days. The current series of experiments examined effects of acutely administered ddC and AZT on spontaneous locomotor activity and acoustic startle responses (with and without pre-pulse) in female Sprague-Dawley rats. Following intragastric administration, ddC reduced locomotion at all but the highest dose, whereas AZT had no significant effect on locomotor activity. Acutely administered ddC had no effect on ASR, whereas AZT increased ASR at the highest stimulus intensity. These data support the use of behavioral testing in the development of the antiviral nucleoside analogues, as behavioral testing may be more effective in identifying the neurologically active agents than is standard toxicity testing.

Echocardiographic score as a predictor of in-hospital cost in patients undergoing percutaneous balloon mitral valvuloplasty.

Percutaneous balloon mitral valvuloplasty (PBMV) is an effective means of palliating mitral stenosis, but it sometimes leads to adverse clinical outcomes and exorbitant in-hospital costs. Because echocardiographic score is known to be predictive of clinical outcome in patients undergoing PBMV, we examined whether it could also be used to predict in-hospital cost. Preprocedure echocardiographic scores, baseline clinical characteristics, and total in-hospital costs were examined among 45 patients who underwent PBMV between January 1, 1992, and January 1, 1994. Patients ranged in age from 18 to 71 years and had preprocedure echocardiographic scores that ranged from 4 to 12. Following PBMV, mean mitral valve area increased from 1.1 +/- 0.3 to 2.4 +/- 0.6 cm2 (p = 0.0001), and mean pressure gradient decreased from 18.3 +/- 5.9 to 6.7 +/- 2.7 mm Hg (p = 0.0001). In-hospital cost for the 45 patients ranged from $3,591 to $70,975 (mean $9,417; median $5,311). Univariate and multiple linear regression analyses demonstrated that among the variables examined, echocardiographic score (p = 0.0007), age (p = 0.01), and preprocedure mitral valve gradient (p = 0.03) were associated with in-hospital cost. Regression modeling suggested that every increase in preprocedure echocardiographic score of one grade was associated with an increase in in-hospital cost of $2,663. Because echocardiographic score is predictive of both clinical outcome and in-hospital cost, we conclude that patients with elevated scores should be considered for alternative therapy.

A novel in vitro assay for human angiogenesis.

Angiogenesis, the development of new blood vessels, is an important process in tissue development and wound healing but becomes pathologic when associated with solid tumor growth, proliferative retinopathies, and rheumatoid arthritis. To date, there has not been a physiologically relevant in vitro model for human angiogenesis that can be used to screen for enhancers and inhibitors of human angiogenesis and allow further investigation of this process. Initially, culture conditions were established for the induction of human angiogenesis in vitro using fragments of human placental blood vessel. Once the assay was validated, it was examined for its ability to detect known inhibitors and enhancers of angiogenesis. The role of endogenous acidic fibroblast growth factor (aFGF), basic fibroblast growth factor (bFGF), and vascular endothelial growth factor (VEGF) in the angiogenic response was also assessed by performing RT-PCR on both the parent vessel and microvessel outgrowths. In addition, neutralizing antibodies against the three growth factors were used to quantify the relative importance of each growth factor in the angiogenic response. A fragment of human placental blood vessel was embedded in a fibrin gel in microculture plates and was found to give rise to a complex network of microvessels during a period of 7 to 21 days in culture. The response did not require the addition of exogenous growth factors, and thus provides a convenient system for testing substances for their ability to stimulate or inhibit a human in vitro angiogenic response. The ability of the well known angiogenesis antagonist, hydrocortisone, in the presence and absence of heparin, and suramin to significantly inhibit the angiogenic response indicated that the model could be used as an efficient in vitro assay for screening inhibitors of human angiogenesis. The presence of mRNA for aFGF, bFGF, and three isoforms of VEGF, as well as their receptors, FGFR1, FGFR2, Flt-1, and KDR, in vessel outgrowths and the parent vessel, as identified by RT-PCR, strongly implicated aFGF, bFGF, and VEGF as having an important role in this neovascularization response. This was further confirmed by the ability of neutralizing antibodies to aFGF, bFGF, and VEGF to inhibit the angiogenic response to varying extent. Furthermore, the response could be enhanced by the addition of these growth factors in serum-starved cultures. Finally, a stimulatory effect was observed when matrigel was incorporated into the fibrin gel, which indicates that components of the extracellular matrix also play an important role in governing the strength of the angiogenic response. A physiologic angiogenic response relevant to wound healing can be generated by culturing fragments of human placental blood vessels in fibrin gels. The growth factors aFGF, bFGF, and VEGF were shown to play an important role in stimulating this spontaneous angiogenic response. This assay, which can be performed in microcultures, was also shown to be an excellent method for screening for potential inhibitors and enhancers of human angiogenesis.

Effects of environmental conditions on food consumption in female and male rats.

The present experiment examined food and water consumption under different housing conditions in 20 female and 20 male Wistar rats. Food and water consumption were measured for 6 h a day following an 18-h same-sex crowded or individual housing period for each of 6 days. All subjects were individually housed during the 6-h measurement period and had access to food and water. Female rats consumed more food and water than did male rats during the 6-h period, regardless of their 18-h housing condition. In addition, previously crowded rats consumed more food and water during the 6-h period than did rats that were previously individually housed. During the 18-h period, when subjects were differentially housed, males consumed more food and water than did females; crowded rats ate less than did individually housed rats; and crowded rats drank more water than did individually housed rats. Based on plasma corticosterone data, the female and male rats were differentially affected by housing conditions. The present results are discussed with regard to housing conditions per se and sex differences in stress responses to housing.